Hillary Clinton calling Donald Trump dangerous again, attempting to clobber him on the economy, as Trump, a man whose name is nearly synonymous with cash, answers questions about why his campaign seems relatively broke.

Breaking news, new details in the Orlando terror investigation. Where the killer went in the hours before the shooting, and what was he doing with three plane tickets?

Plus, Democrats accusing Republicans of selling guns to ISIS? This after a series of gun control measures die in the Senate, and today the White House frankly may have added more ammo to the clip.

HILLARY RODHAM CLINTON (D), PRESIDENTIAL CANDIDATE: We cannot put a person like this, with all his empty promises, in a position of power over our lives. We can't let him bankrupt America like we are one of his failed casinos.

(END VIDEO CLIP)

TAPPER: Clinton is hoping to exploit any potential weaknesses in her rival after an unsteady few weeks in his campaign. And now the businessman finds himself lagging behind Hillary Clinton in how much money their campaigns have in the bank, what's called cash on hand.

He's behind her to the tune of $40 million.

We have got reporters covering both presidential campaigns this afternoon. We're going to begin with CNN's senior White House correspondent, Jim Acosta. He's live outside Trump Tower. Jim, Mr. Trump trying to regain the offensive this week, turning the

focus back on his Democratic opponent.

JIM ACOSTA, CNN SENIOR WHITE HOUSE CORRESPONDENT: That's right, Jake.

And Donald Trump is working in overdrive, trying to reassure Republicans that he is running a credible campaign after some downright awful fund-raising numbers, but there is one sign of life for his campaign, in that is it hitting back at Hillary Clinton in ways it hasn't before.

(BEGIN VIDEOTAPE)

ACOSTA (voice-over): Despite a lifetime of cutting deals that made him billions of dollars, Donald Trump is so short of campaign cash, GOP jaws are dropping. But don't worry, says Trump.

DONALD TRUMP (R), PRESIDENTIAL CANDIDATE: This weekend, we had a very big fund-raising weekend. It's not revealed yet, but we raised a lot of money.

ACOSTA: Still, consider the numbers. According to federal campaign filings, Hillary Clinton finished the month of May with $42 million in the bank. Trump ended up with a tiny fraction of that haul, just $1.3 million. Other glaring findings this month, 17 percent of the campaign spending was dished out to Trump-related entities, like when the campaign rents space from a Trump property for an event and $35,000 went to somebody called Draper Sterling.

JON HAMM, ACTOR: It's right on strategy.

ACOSTA: An expenditure with a name reminiscent of the advertising agency in the hit show "Mad Men."

Trump released a statement on his fund-raising, noting his appeals to donors are just beginning, adding, "If need be, there could be unlimited cash on hand, as I would put up my own money." Earlier in the day, he blamed Republicans who haven't rallied behind his campaign.

TRUMP: They don't want to come on. They will probably eventually come on. Honestly, if they don't, it's just fine. I can win it either way.

ACOSTA: Nothing to see here, added the RNC.

UNIDENTIFIED MALE: I appreciate everyone's concern over the state of our party. We're doing just great.

ACOSTA: Still, there are other worrying numbers for Trump. He trails Hillary Clinton by five points in a new CNN/ORC poll. And a new Quinnipiac swing state poll shows Trump down eight points in Florida while running neck and neck in Ohio and Pennsylvania.

But Trump is signaling a more aggressive stage of the campaign is just ahead. His campaign is blasting out e-mails and hitting social media to counter Clinton's latest attacks, responding faster than it has before.

TRUMP: And she's been there watching.

ACOSTA: Trump advisers are hopeful it's a change for the better after the firing of campaign manager Corey Lewandowski. The candidate was also out shoring up support among evangelical leaders gathered in New York.

TRUMP: Christianity, I owe so much to it in so many ways, through life, through having incredible children, through so many other things, but I also owe it from frankly standing here, because I -- the evangelical vote was mostly gotten by me.

(END VIDEOTAPE)

ACOSTA: And Trump has a speech aimed at attacking Clinton set for tomorrow. Of course, she was doing the same to him earlier today, but a big difference, Jake. Unlike past speeches from Hillary Clinton attacking Donald Trump, today, the Trump campaign was offering sort of a prebuttal to that speech, something it hasn't done before.

Hillary Clinton finds herself out ahead of Trump in fund-raising and campaign organization, but, as Jim noted, fresh polls from battleground states, Pennsylvania and Ohio, show that regardless of her few good weeks and a rough few more Mr. Trump, the two candidates remain neck and neck in two very valuable pieces of electoral wealth.

Brianna, Hillary Clinton might be ahead in our latest national head- to-head poll, but voters are still giving Trump higher marks on the economy and creating jobs.

BRIANNA KEILAR, CNN SENIOR POLITICAL CORRESPONDENT: Yes, significantly higher marks, and this is something, of course, the Clinton campaign is taking note of.

The economy, Jake, is the issue that voters say is what matters to them most, and so Hillary Clinton has a lot of work to do.

(BEGIN VIDEOTAPE)

KEILAR (voice-over): Hillary Clinton hitting Donald Trump on his experience as a businessman.

CLINTON: He's written a lot of books about business. They all seem to end at chapter 11.

(LAUGHTER)

KEILAR: Taking aim at him for going into bankruptcy with four of his corporations and for once calling himself the king of debt.

CLINTON: The king of debt has no real for making college debt payable back or making college debt-free. This is a crisis that affects so many of our people. He has no credible plan for rebuilding our infrastructure, apart from the wall that he wants to build.

KEILAR: But Trump is embracing the moniker, tweeting, "I am the king of debt. That has been great for me as a businessman, but is bad for the country. I made a fortune off of debt, will fix U.S."

Many voters agree. In a new CNN/ORC poll, when asked who would better handle the economy, 51 percent of those polled said Trump, Clinton trailing him by eight points. Her campaign is trying to change that, putting up a new Web site in conjunction with her economic speech, theartofthesteal.biz, a play on his bestselling book "The Art of the Deal," and releasing a video about Trump's unsuccessful business ventures.

JOHN OLIVER, HOST, "LAST WEEK TONIGHT WITH JOHN OLIVER": "Trump" magazine, which folded, "Trump World" magazine, which also folded.

ROMNEY: And Trump mortgage.

KEILAR: But as Clinton trails Trump on handling of the economy in the polls, she's crushing him on fund-raising, with $42 million in the bank to Trump's $1.3 million.

That's not her only advantage over the presumptive GOP nominee. The latest CNN poll also shows voters see Clinton as having the better temperament to serve as president by a 24-point margin. Clinton today seeking to connect those doubts with putting Trump in charge of the U.S. economy.

CLINTON: Just like he shouldn't have his finger on the button, he shouldn't have his hands on our economy.

(END VIDEOTAPE)

KEILAR: And as Hillary Clinton's anti-Trump rhetoric heats up, so does the speculation about who her running mate is going to be.

The names in close consideration, CNN has learned, include Tim Kaine and Elizabeth Warren, as well as Housing and Urban Development Secretary Julian Castro and Labor Secretary Tom Perez.

And also, Jake, kind of interesting, one Ohio senator, Sherrod Brown, who has a very good rapport with Hillary Clinton. When are we going to find out? It might not be until around the Republican Convention here in about a month.

TAPPER: All right, Brianna Keilar, thanks so much.

Let's bring in Republican Congressman Adam Kinzinger of Illinois.

Congressman, first of all, let me just get your reaction to the fact that, according to these FEC reports, Hillary Clinton has $42 million cash on hand. Donald Trump has $1.3 million. You want Republicans to win the White House, although I know you're unsure about Mr. Trump himself.

REP. ADAM KINZINGER (R), ILLINOIS: Yes.

TAPPER: But that's got to be alarming in terms of fund-raising.

KINZINGER: Yes, it's hugely alarming.

And I think this goes to show Donald Trump has tried to make it a point that he doesn't need to run a traditional campaign. Well, you really do. You need fund-raisers. You need people that can work and organize on the ground.

One of the more astonishing is, Donald Trump has 70 employees and Hillary Clinton has something like 700 working to organize in the field. That's worth a lot of percent at the end.

I think part of the problem you run into is -- and it happens with any so-called self-funding candidate -- is, if the say, well, I can just write a check myself, you have a lot of small donors that go, well, then he doesn't need my $100 or $50 if I'm just basically displacing what he's going to write anyway. And, so, yes, I think it's very concerning.

TAPPER: I think big donors have been saying that too.

Have you heard from -- look, you have to fund-raise like every other public official in this country. Have you heard from donors saying that they're not going to give money from Trump and, if so, why?

[16:10:02]

KINZINGER: Yes, I talked to -- I was talking with a big donor, e- mailing with one today, who basically said he's staying out of the presidential race. He's going to help House and Senate Republicans to hold the House and Senate.

Look, they're concerned the same reason I am, the same reason I'm not supporting Donald Trump, is because I think temperament. I think spending more time attacking fellow Republicans, not doing what's necessary to unite. And we have seen his comments.

A lot of these donors are really concerned with foreign policy, the role of America in the world. And we have seen a front-runner that basically praises Vladimir Putin and condemns David Cameron because he calls him a meanie.

TAPPER: Now, you say not supporting Donald Trump. Is that forever or that's just right now?

KINZINGER: Well, no, I'm not a never Trump guy, because, in my mind, to say never, then you're basically saying, doesn't matter what you do, doesn't matter if you come and start showing that you're a Republican or whatever. I'm a not there yet guy.

And each day that goes by, it's becoming harder and harder to see how I get there, but I really want to. I would love to support the Republican nominee, but as I have said, I'm an American before I'm a Republican, and I have to put it through that filter first.

TAPPER: Do you not worry that your position really helps hand the election over to Hillary Clinton?

KINZINGER: Well, sure, it's a concern. Look, I'm not going to be the defining vote in Illinois. Illinois is a pretty Democratic state.

(CROSSTALK)

TAPPER: Right. But there's an aggregate of all of you saying these things that might help tip the election towards...

KINZINGER: Well, it's a concern, but, look, as a -- I have a lot of serious concerns with Donald Trump.

And I take my position -- you know, I'm a private citizen. I hold nothing against people who supported Donald Trump. I understand it. But as a citizen who happens to be a member of Congress, people ask my opinion, and my opinion is, I have a hard time getting to yes on Donald Trump.

And I definitely don't want Hillary Clinton to win, you know, but at the end of the day, the uniting of the party is on Donald Trump. It's not on people like me. It's not on members of Congress. It's on the front-runner. You see that in the Democratic Party as Hillary Clinton tries to bring some of the Bernie Sanders folks on board.

TAPPER: So if the election were today, what would you do?

KINZINGER: I would probably write in a Republican's name and I'm not sure who yet.

TAPPER: Interesting.

Let me ask you a question. You're not just a member of Congress and a private citizen. You're also a veteran who must have opinions about who would be a better commander in chief.

KINZINGER: Yes.

TAPPER: Would you be more comfortable with Hillary Clinton as commander in chief than you would Donald Trump? And the reason I ask is because I think your foreign policy is closer to hers.

KINZINGER: Well, I'm not going to say I would be more comfortable with one or the other.

I have concerns with both of them. And I have real deep concerns with Donald Trump. You know, at the end of the day, I hope that over the next five months Donald Trump can begin to articulate a foreign policy that I agree with, at least in some level. I don't have to agree with him on 100 percent, but appears Republican and Reaganesque. He's just not there yet.

TAPPER: But can I just translate?

KINZINGER: Yes.

TAPPER: You just said you have concerns about both of them, but then you said you have real deep concerns about Donald Trump.

KINZINGER: Yes. And I...

TAPPER: That suggests that you have more concerns about him than you do about her.

KINZINGER: Well, and I have real concerns about Hillary Clinton too. You look at the postgame in Libya. And I supported intervention in Libya, but we turned our back in the postgame, and the lack of action in Syria has been a big problem too.

TAPPER: All right, Congressman, good to see you. Thanks so much for being here.

Why is Donald Trump struggling to fund-raise and should the campaign be concerned about it? That's next.

Plus, new information about what the Orlando terrorist was doing the night of the shooting, including a visit to the Pulse nightclub just hours before the attack. Stay with us.

(COMMERCIAL BREAK)

[16:17:21] TAPPER: Welcome back to THE LEAD.

As Donald Trump looks to right his campaign, Hillary Clinton is hoping to take advantage of her seeming organizational edge.

Kayleigh, let me start with you. Why is Mr. Trump having trouble bringing in fund-raising dollars and can this be fixed?

KAYLEIGH MCENANY, DONALD TRUMP SUPPORTER: It can be fixed, because let's be real. Donald Trump just started fundraising. He hasn't been out there trying to get money. He hasn't been sending the e-mails. He hasn't been promising to match it.

So, this is all just starting. Should it have started earlier? Perhaps. But it's worth mentioning that Donald Trump has defied conventional wisdom every step of the way. Three opposing candidates in the primary, Rubio, Cruz, and Bush, all spent upwards of $100 million. He spent just half that and won.

This is a general election. You need cash but the RNC has cash. He's going to bring in cash. He's going to change. It's going to change now and I think that he will defy conventional wisdom again.

TAPPER: Kayleigh as always comes better prepared to these things than I do and she just basically said my second question, which is to you Ana.

Donald Trump has defied conventional wisdom before. He was outspent during the primaries. Is it possible it doesn't matter as much as we think it does?

ANA NAVARRO, REPUBLICAN STRATEGIST: I guess at this stage of the game, it does matter because infrastructure starts to matter. You have got to pay payroll. You've got to make payroll. The expenses start mounting up. There are some expenses that can only be paid by the hard money of a campaign.

I think what you're seeing is that I don't care how rich you are and donors today can be very, very wealthy, no matter how rich you are, nobody likes to throw money away. They need to feel confidence that he is running a well-run campaign, that he's got the staff, that he's got the messaging, he's got a plan, and he's not showing that. And that's what you're seeing in those number, it's lack of confidence.

TAPPER: And, Paul, let's be frank. Donald Trump had a few rough weeks, not good for his campaign. And yet the polls don't really seem to reflect that in every place. Look at the polls we have here. In Ohio, Trump and Clinton are basically tied. Pennsylvania, which nearly always goes Democratic, Clinton is up by only 1 percent.

She should be doing much, much better one would think after these last few weeks.

PAUL BEGALA, CNN POLITICAL COMMENTATOR: Yes, short answer, but she is doing better than she was a few weeks ago. Don't forget, she's -- her primaries ended later.

TAPPER: Not in those states though.

BEGALA: Yes, in those states. The Quinnipiac poll a few weeks ago was better for Trump than they are today. That's Quinnipiac. I generally don't do this in public. They did survey these over 11 days, and so, it makes it a little suspect. That's too long. You know, polls are snapshot in time. If you're moving that camera that much, it's going to be blurry.

[16:20:00] By the way, the same series of Quinnipiac polls released today has Hillary up eight in Florida.

TAPPER: Yes, Florida. I didn't put that up in my banner.

BEGALA: Right, but the president won that by less than one point.

TAPPER: But shouldn't she be cleaning his clock is my point?

BEGALA: And she will, but it will not be easy. I do not want Democrats to give in to this irrational exuberance. I'm with Kayleigh, I think is all is well in Trump land. He doesn't need money, organization or campaign.

TAPPER: Oh, cut it out.

BEGALA: But Hillary does. And she has got to fight if she wants to win this thing. It's not going to be easy. So, I don't think Democrats are going to be counting their eggs or chickens or whatever.

NAVARRO: He's such a veteran sarcastic humor.

(CROSSTALK)

TAPPER: I know. So smart and once again, so here we have stepping on my question to you, Kayleigh.

Let's look at the numbers out of Florida. Clinton leads Trump by eight percent. Quite a bit of that is because of how strong she is and how weak he is with nonwhite voters. If he does not win Florida, that could make his election effort much more difficult. Can he improve his standing in Florida especially with minority voters?

MCENANY: I think he can and you're exactly right. He needs to win Florida. The map becomes imminently easier to dominate and to win with Florida.

I think the key for him there is to emphasize how the Obama economy has hurt minorities. They're still facing double digit real unemployment. Wages are stagnant. He needs to reach out to millennials and minorities in that regard and focus on the economy.

And every time he's asked about the judge or something else, hammer back the economy because that is what people care about and that is his way to resonate with minority voters.

TAPPER: But that's not very Trumpian.

Ana, here is how Mr. Trump responded to Hillary Clinton's speech on the economy today. He wrote, "I am the king of debt." That was something he had said that she hammered him for. "I am the king of debt. That has been great for me as a businessman but it's bad for the country. I made a fortune off of debt, will fix U.S."

Is that Trump taking Kayleigh's advice and staying on message?

NAVARRO: I think it's Trump doing what he does, which is answering through 140 character tweets. At some point, he's going to need to answer with a lot more detail. At some point, he's going to need to release tax returns.

I think Hillary Clinton is, you know, taking him apart piece by piece. First, foreign policy, now on what he supposedly brings to the table, economic forte, knowledge of business, executive experience.

If he can't even run his own campaign, if he can't en fund his own campaign, you begin to question, does the emperor have no clothes on? This is what his forte is. This is what he's bringing to the table.

So, she's smart to be trying to define him this early on. I think it's something that a lot of his opponents in the primary missed the chance to do.

TAPPER: Well, his opponents, yes, they missed many opportunities.

Paul, I need to ask you this because our Jeff Zeleny is reporting these are the names that team Clinton is looking at for their V.P. pick: Senator Elizabeth Warren of Massachusetts, Virginia Senator Tim Kaine, HUD Secretary Julian Castro, Labor Secretary Thomas Perez, Ohio Senator Sherrod Brown, and California Congressman Javier Becerra.

If you were advising here and don't all be politic now, if you were advising her, who would tell her to pick?

BEGALA: Honestly, what I would say, I learned from her husband and I watched President Obama do it, frankly, President Bush, too -- if you only pick someone for the campaign, you will make a bad pick. It will, first of all, be politically bad. It seems odd but if you try to be too political it will blow up. There are two qualifications.

TAPPER: But you're saying Clinton and Bush did not do that.

BEGALA: Correct.

TAPPER: Governing picks.

BEGALA: Clinton, Bush, and Obama, all three of our last three presidents I believe picked one for the right reason. In Bush's case, if something happened to me, God forbid, who could rule the country in my place, it's Cheney. He shot a man in the face.

TAPPER: I don't think that's --

BEGALA: No, but honestly, I do admire the thought process. Bush didn't need Cheney's animal magnetism or Wyoming's three electoral votes. He made a governing pick. I don't agree with their governing policy, but he made a governing pick.

Hillary needs to do the same thing.

NAVARRO: You know, he asked you one question. Pick one person out of --

BEGALA: I will not.

TAPPER: I get the explanation. You're not going to give me a name?

BEGALA: No way. Who can run the country, God forbid if something happens to the president, and who can be a good governing partner if nothing bad happens to the president.

TAPPER: Ana, thoughts? Who would you thought that Hillary pick?

NAVARRO: I wouldn't pick Elizabeth Warren because I think she's got a chance to pick off some moderate Republicans who are going to have the bejesus scared out of them if it's Elizabeth Warren.

TAPPER: So, what, Tim Kaine?

NAVARRO: I think Tim Kaine is a smart pick. He also knows how to speak Spanish. Spent time in Honduras. So he will bring -- he's not a Hispanic, but he will bring appeal towards Hispanics.

TAPPER: Ten seconds, Kayleigh. Who would you pick if you were advising Hillary Clinton which I know you would never do?

MCENANY: I would pick Castro. She has a millennial problem. She needs some youth and vitality and that would do that.

Coming up later, meet the libertarian presidential candidate, presidential ticket at the CNN libertarian town hall with Gary Johnson and William Weld. That will be moderated by Chris Cuomo. That will be live Wednesday night at 9:00 p.m.

Three plane tickets to California for a trip in July. That's what law enforcement now says the Orlando terrorist purchased the day before he carried out the worst terror attack since 9/11.

(COMMERCIAL BREAK)

[16:29:22] TAPPER: Welcome back.

We're back with the national lead now and major developments today in the Orlando terror investigation as investigators try to retrace the steps of the killer. They're learning that he visited Pulse nightclub hours before shooting up the place. Investigators say he came to the club, left, then came back and killed 49 people in cold blood.

Investigators also say that before the shooting, the Orlando terrorist bought three plane tickets which raises even more questions about his larger plan.

CNN justice correspondent Pamela Brown has been working her sources and joins me now.

Pamela, the terrorist had an argument with his wife before the rampage as you tell me.

PAMELA BROWN, CNN JUSTICE CORRESPONDENT: That's right.

TAPPER: What was it about?

BROWN: So, we're learning from officials that he left the house angry that day, and he left with a bag of guns. That is what the wife is telling investigators.